As in other machinery having a rotating vertical shaft, most scroll machines commonly provide oil to bearings requiring lubrication by means of an oil passage that extends through the shaft. The oil is typically conveyed up this passage from a reservoir in which the lower end of the drive shaft is immersed, and is supplied to each bearing through radial side passages. This system works well for supplying oil to drive shaft bearings and other bearing surfaces directly accessible from the central shaft oil passage, but generally cannot efficiently supply lubricant to bearings that are spatially separated from the passage, particularly if such bearings must receive a substantial proportion of the total lubricant flow.
This problem is addressed in U.S. Pat. No. 4,403,927 which has been assigned to the same assignee as the present application. The invention disclosed therein provides an oil collector cup around the top of the passage through the drive shaft. The collector cup is connected to the lower surface of the swing link and underlies both a swing link bearing and a passage formed adjacent the swing link bearing, in fluid communication with a thrust bearing and the sliding surfaces of an Oldham coupling. An arcuate-shaped baffle disposed immediately below the swing link bearing deflects a portion of the oil flowing into the cup upward, into the swing link bearing. The remainder of the oil is available to lubricate the thrust bearing and Oldham coupling.
Although the oil distribution system described in U.S. Pat. No. 4,403,927 operates well to proportionately allocate oil between the bearings, it has several deficiencies that have become evident during manufacturing design development. It has been found difficult to fabricate the collector cup and arcuate baffle with the necessary axial tolerance to insure that the top of the baffle is in contact with the bottom of the swing link bearing. If there is a gap between the baffle and the bearing, oil that should flow upward into the swing link bearing from the collector cup instead leaks through the gap. Thus, the swing link bearing does not receive adequate lubrication.
The collector cup/baffle is also somewhat expensive to manufacture and assemble. In addition, the groove or passage formed in the swing link (adjacent its bearing and used to convey oil to the thrust bearing and Oldham coupling) compromises the support of the swing link bearing.
In consideration of these problems, it is an object of the subject invention to distribute oil to the bearings of a scroll machine in proportion to their requirements for lubrication.
It is a further object to distribute oil between a swing link bearing, and a thrust bearing and the sliding surfaces of an Oldham coupling in predetermined proportion as required to meet their lubrication needs.
Yet a further object is to provide a relatively low-cost oil distribution system for a scroll machine.
These and other objects of the invention will become apparent from the description of the preferred embodiment which follows and by reference to the attached drawings.